Refilling service fee to a prepaid cell phone service is a common practice. A user can refill or prepay a certain amount of money for his/her cell phone beforehand, and the service provider can deduct an actual service charge directly from the prepaid amount. In this way, the user does not need to visit the service provider's store to pay a bill.
Similar refill activities have been used in more and more scenarios, such as refill of virtual currency/game currency, refill of online game time, and refill of smart electricity cards over the Internet. Usually, each refill account has a unique account number, and the refill procedure is to associate the refill amount with a corresponding account number, thereby providing a prepaid credit for future debits.
The account number of the refill account is generally formed by a plurality of numbers, letters, etc. As a result, when the user inputs the account number manually, it is easy to make mistakes. If the user does not check the input account number carefully, it may cause refilling of an incorrect account number, thereby resulting in financial loss.